Following baobab's method I could finish this challenge.It is shocking that given the right strategy (walling off the two neighbours first, then killing them while grabbing ressources in the middle and walling in) I encountered no resistance whatsover.AI armies did not go out of its bases at all, in the whole game.My defences did not take any blow except when they were within range of enemy units in their bases.Shocking.

Sorry I think this was a bug in the AI that its armies did not move at all, caused by a glitch between load/save.Starting again from the start, the AI is agressive, as it should be, and this map still is a challenge.If my previous post and this one could be deleted...

I remember actually finishing this challenge successfully a couple years ago, on one of the late 2.x builds. Slow game down as much as you can, have 10+ basic mg viper wheels tanks start attacking bases from the start and have whatever trucks you can get follow them around, building over the seized oil derricks. Have factories continue to produce machinegun viper wheels while researching machinegun and tank armor upgrades, keep pumping out machineguns and eventually heavy machineguns, while having your trucks build derricks wherever they can, a couple MG towers next to them and a power generator for every 4, as well as building an extra factory over every base you take to mass units. It's extremely difficult and a lot of it comes down to luck, but it IS possible with perfect micromanagement, made possible with speed settings.